Recent content by James O'Neill

Thank you for your help. I grasp it now. (20 x 0.125 ) -(8 x 0.05) = 2.1 kg m. Won't topple over.

So let's make the weight 10 cm long. (20 x 0.05 kg m) - (8 x 0.05 kg m) = 0.6 kg m. Is it right this time? Can you then adjust this formula to calculate counterweight needed?

Ohhh... I thought since you said sum in your second message I had to add the two together. This makes sense. If the 8kg weight was directly against the side of the box, it would also stay up, right? (20 x 0.125 kg m) - (8 x 0.125 kg m) = 1.5 kg m.

I'm having some trouble seeing how you got 0.7 kg m at the end?? Also just curious, does three dimensional properties (l x h x w) have any effect on this?

I have made a sketch as example.

In tower cranes counterweights are placed on the counter jib to prevent the crane from falling over. Whereas on mobile cranes the counterweights are placed directly behind the cabin. The crane in itself also acts as some counterweight. My question to you is: How much weight can an object support...

Sorry for the late reply. I hope there are still people interested. I dug around on the internet and found low RPM permanent magnet alternators (usually used in small wind turbines), that put out 12 Volts at 135 RPM. I also did calculations to get the RPM of the Tesla Model S' half shaft = ±143...

The funnel has a rectangular cross section. If the funnel is circular, does one use the circumferences? Also, if the tide is 3 m/s, won't the water enter the funnel at 3 m/s?

Abig = 8 m x 6.75 m = 54 m2 Asmall = 4 m x 6.75 m = 27 m2 So ρubigAbig = ρusmallAsmall 4096 kg/m2s x 54 m2 / 27 m2 = 8192 kg/m2s Thus ρusmall = 8192 kg/m2s ?? Is this right ?? What would the velocity be then?? Perhaps 8192 / 1024 kg/m3 (ρusmall / water density) = 8 m/s That gives me 8 m/s which...

So if you say density, do you mean the density of sea water? If so, then: ρ = 1024 kg/m3 u = 4 m/s Abig = 54 m2 Δt = 5 mins Asmall = 27 m2 ρu x Abig = 4096 x 54 = 221 184 221 184 x Δt = 221 184 x 5 = 1 105 920 ρu x Asmall = 4096 x 27 = 110 592 x 5 = 552 960 Is this right so far? (It doesn't...

I want to calculate the water velocity as it exists the smallest part of the funnel. So probably

Hello people of PF. My name is James O'Neill and I am a student from South Africa. I've been on Physics Forums for about a week now... Just wanted to say thanks to everyone that have helped me so far. I also just want to send a shout out (do scientists do that?) to the people who created and...

I have seen some tidal turbines that have funnel ducts around them to improve efficiency. So how would one calculate water acceleration in a funnel? If you want figures: water velocity - 3 m/s funnel opening A (largest) - 8 meters funnel opening B (narrowest) - 5 meters Distance between A and...

Yes, bar magnets. Every second magnet's north pole is facing outward.

Let's say the gear has 18 teeth and the magnets are set up as in the image below. Basically I want to know, what effect would a magnetic gear have in a gearbox...